Why does your lower stomach protrude when the rest of your body is unflabby?

When you eat fatty food and don't do exersize in the next 2 hours your body stores up the food and leaves it in your stomach. Causing it to stick out. If your stomach sticks out you are most likely to have put on weight. For example: The other day I put on my bikini and I looked fine and then a couple of days later I put it on again and my stomach was sticking out. So I weighed myself and found out that I had put on 2 kilograms.